CN111699092A - Polyester film - Google Patents

Polyester film Download PDF

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Publication number
CN111699092A
CN111699092A CN201980012433.XA CN201980012433A CN111699092A CN 111699092 A CN111699092 A CN 111699092A CN 201980012433 A CN201980012433 A CN 201980012433A CN 111699092 A CN111699092 A CN 111699092A
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China
Prior art keywords
polyester film
layer
particles
particle
containing layer
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Granted
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CN201980012433.XA
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Chinese (zh)
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CN111699092B (en
Inventor
中山慧美
栋泰人
川崎泰史
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Mitsubishi Chemical Corp
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Mitsubishi Chemical Corp
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
    • B32B27/20—Layered products comprising a layer of synthetic resin characterised by the use of special additives using fillers, pigments, thixotroping agents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/06—Interconnection of layers permitting easy separation
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/04—Coating
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields
    • H05K9/0073—Shielding materials
    • H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields

Abstract

A novel polyester film for use in transfer applications having a roughened film surface, which has excellent visibility, i.e., visibility, and which, even when a release layer is formed, does not smooth the roughened state and can impart a desired matte feeling to an object. A polyester film characterized by comprising: the polyester film is characterized by having a structure in which a release layer is formed on the surface of a particle-containing layer of a polyester film substrate having a particle-containing layer containing particles having an average particle diameter of 2.0 [ mu ] m or more, and the polyester film has a transmission concentration OD value of 0.10 or more.

Description

Polyester film
Technical Field
The present invention relates to a polyester film having a release property, which can transfer a matte appearance.
Background
Polyester films represented by polyethylene terephthalate and polyethylene naphthalate are used for various applications because they have excellent properties such as mechanical strength, dimensional stability, flatness, heat resistance, chemical resistance and optical properties and are excellent in cost performance.
As an example of the use of the polyester film, an electromagnetic wave shielding use can be given. In a Plasma Display Panel (PDP) or the like, an electromagnetic wave shielding film, that is, a conductive film is attached to a front surface of a display panel, and as the electromagnetic wave shielding film, a conductive film in which a mesh-like fine metal wire is provided on a polyester film is generally used.
As such an electromagnetic wave shielding film, the following operations are performed: an electromagnetic wave shielding film is formed on a support film, and the electromagnetic wave shielding film is transferred by pressure-bonding the electromagnetic wave shielding film to the surfaces of various devices at a high temperature.
As a support film for such a transfer-type electromagnetic wave shielding film, a flat polyester film has been generally used. However, in order to dull the appearance of the product and finish the appearance, the following proposals are made: a polyester film having a surface finished into a matte finish is used for the support film, and the matte finish surface is transferred to an article.
For example, patent document 1 discloses a biaxially oriented release polyester film comprising a base film and, superimposed on the a layer of the base film, a coating layer mainly composed of a melamine resin, wherein the gloss of the surface on which the coating layer is superimposed is 30 or less, and wherein the base film comprises, as the outermost layer, a polyester a layer containing 0.1 to 10 mass% of inorganic particles and/or organic particles, based on 100 mass% of the entire polyester a layer.
Patent document 2 discloses a biaxially oriented polyester film, which is a laminated polyester film having a base material layer and a matte layer containing particles on at least one surface thereof, wherein the matte layer has an average surface roughness (Ra) of 400 to 1000nm, an average roughness at 10 points (Rz) of 4000 to 8000nm, a glossiness in the surface (G60) of 6 to 20, and a void breakage rate of protrusions on the surface of 20% or less.
Patent document 3 discloses a biaxially oriented polyester film for mold release, which comprises a polyester a layer containing inorganic particles and/or organic particles in at least one outermost layer, wherein the average surface roughness Ra of the polyester a layer surface of the outermost layer is 0.38 μm or more and 1.0 μm or less, and the average width RSm of the contour elements of the polyester a layer surface is 10 μm or more and 80 μm or less.
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open publication No. 2015-66805
Patent document 2: japanese patent laid-open publication No. 2016-97522
Patent document 3: japanese patent laid-open publication No. 2016-175229
Disclosure of Invention
Problems to be solved by the invention
As described above, the surface of the polyester film is roughened to be matte, and the surface of the polyester film is brought into contact with the surface of an object and pressure-bonded thereto, and then the polyester film is peeled off, whereby the roughened surface state can be transferred to the surface of the object, and the surface can be finished to have a matte appearance.
Since such a transfer polyester film proposed in the past is required to form a release layer by laminating a release film on the surface of the polyester film or applying a release agent, the roughened state of the surface of the polyester film is smoothed when the release layer is formed, and a desired matte feeling may not be imparted to the surface of an object.
In addition, as a polyester film having a release property, excellent visibility, i.e., visibility is sometimes desired.
Accordingly, a 1 st object of the present invention is to provide a novel polyester film which has a roughened film surface and is used for applications of transferring the surface state of the film, has excellent visibility, i.e., visibility, of the polyester film at the time of transfer, and can impart a desired matte feeling to an object without smoothing the roughened state even if a release layer is formed.
The 2 nd object of the present invention is to provide a novel polyester film which prevents curling (curl) of the entire polyester film, improves handling properties, and can improve adhesion to a product in which the polyester film is laminated.
Means for solving the problems
In order to achieve the above object 1, the present invention provides a 1 st polyester film comprising a polyester film base material having a particle-containing layer containing particles having an average particle diameter of 2.0 μm or more, wherein the polyester film has a transmission concentration OD value of 0.25 or more.
In order to achieve the same object as the above 1, the present invention provides a 2 nd polyester film comprising: the polyester film is characterized by having a structure in which a release layer is formed on the surface of a particle-containing layer of a polyester film substrate having a particle-containing layer containing particles having an average particle diameter of 2.0 [ mu ] m or more, and the polyester film has a transmission concentration OD value of 0.10 or more.
In order to achieve the above-mentioned 2 nd object, the present invention proposes a 3 rd polyester film comprising a polyester film base material, wherein the polyester film base material comprises a particle-containing layer a containing particles having an average particle diameter of 2.0 μm or more on one side of a base material layer, and a particle-containing layer B containing particles having an average particle diameter of 2.0 μm or more on the other side of the base material layer, and the content of the particles having an average particle diameter of 2.0 μm or more in the particle-containing layer B is smaller than that in the particle-containing layer a.
ADVANTAGEOUS EFFECTS OF INVENTION
The 1 st and 2 nd polyester films proposed in the present invention can be provided in a state of being provided with a release layer, and therefore, when the release layer is formed, a desired matte feeling can be given to an object without smoothing the roughened state of the polyester film surface. Further, since the transmission density OD value of the polyester film is 0.10 or more or 0.25 or more, the visibility of the polyester film at the time of transfer, that is, the visibility is excellent.
The 3 rd polyester film proposed by the present invention is a polyester film characterized by comprising a polyester film base material having particle-containing layers A, B on both sides of the base material layer, wherein the content of particles having an average particle diameter of 2.0 μm or more is smaller in the particle-containing layer B than in the particle-containing layer a, and the particle-containing layers A, B on both sides of the base material layer, and therefore, curling of the entire polyester film can be prevented. Further, while the matte feeling is imparted to the surface of the object on the surface side of the particle-containing layer a, the particle-containing layer B can ensure suitability for surface processing by making the content of the particles smaller than that of the particle-containing layer a, and a desired layer can be easily laminated on the surface of the particle-containing layer B, so that, for example, adhesion to a product to be laminated can be improved.
Drawings
FIG. 1 is a cross-sectional view showing an example of the structure of a polyester film according to an embodiment of the present invention.
Detailed Description
Next, the present invention will be described based on embodiment examples. However, the present invention is not limited to the embodiments described below.
The polyester film 1
A polyester film (referred to as "the present polyester film 1") according to an embodiment of the present invention is a polyester film including a particle-containing layer a containing particles having an average particle diameter of 2.0 μm or more.
The polyester film 1 may be a non-stretched film (sheet) or a stretched film. Among them, a stretched film stretched in a uniaxial direction or a biaxial direction is preferable. Among them, a biaxially stretched film is preferable in terms of excellent balance of mechanical properties and flatness.
The polyester film 1 may be composed of only a polyester film having a particle-containing layer a containing particles having an average particle diameter of 2.0 μm or more, or may be formed by laminating another layer on the polyester film.
(10) the polyester film
A polyester film (referred to as "the present polyester film 10") according to another embodiment of the present invention is a polyester film having the following structure: a releasing layer is formed on one side or both sides of the polyester film substrate.
The laminate structure of the present polyester film 10 may be a structure in which a release layer is formed on one surface of a polyester film base material and the surface of the polyester film base material is directly formed on the other surface, or a structure in which another layer is formed on the other surface. Further, a release layer may be formed on both sides of the polyester film base.
Further, another layer may be provided between the polyester film base material and the release layer.
But the release layer is preferably at least one of the outermost surfaces.
< polyester film substrate >
The polyester film substrate preferably has a particle-containing layer A containing particles having an average particle diameter of 2.0 μm or more. That is, the present polyester film 1 is preferably used as a polyester film substrate. Thus, the following description of the polyester film substrate can be the description of the present polyester film 1.
The polyester film substrate may be composed of only the particle-containing layer a, or may be provided with the particle-containing layer a on one side or both sides of the substrate layer. As a specific example of the latter, for example, the particle-containing layer a may be provided on both sides of the base material layer, the particle-containing layer a may be provided on one side of the base material layer, and the particle-containing layer B different from the particle-containing layer a may be formed on the other side of the base material layer, the particle-containing layer a may be provided on one side of the base material layer, and no layer may be formed on the other side of the base material layer, or the particle-containing layer a may be provided on one side of the base material layer, and a layer containing no particles may be formed on the other side of the base.
Among them, the polyester film substrate is preferably constituted as follows: this configuration will be described in detail later, since the particle-containing layer a is provided on one surface of the base material layer and the particle-containing layer B different from the particle-containing layer a is formed on the other surface of the base material layer.
The polyester film substrate preferably has a transmission concentration OD of 0.10 or more.
A transmission density OD value of 0.10 or more means that the opacity is high, in other words, the whiteness is high and the whiteness is higher.
From the above viewpoint, more preferably 0.10 to 1.0, and still more preferably 0.15 or more or 0.90 or less, further preferably 0.20 or more or 0.80 or less, further preferably 0.25 or more.
When the transmission density OD value of the polyester film base material is in the above range, visibility, namely, visibility is good, and therefore, the present polyester film 10 is easily peeled off after transferring the rough surface to the transfer target.
As a method for adjusting the transmission concentration OD of the polyester film substrate to 0.10 or more, for example, the following known methods can be used: contains a white pigment; or a material having a large difference in refractive index from the main component resin of the base material; or stretching the film containing the fine particles so that voids are formed in the film substrate; and the like.
When the white pigment, for example, the metal compound particles are contained to achieve white color, for example, the metal compound particles are contained in any one of the substrate layer, the particle-containing layer, and the layer provided on the opposite side of the substrate layer from the particle-containing layer, or 2 or more layers thereof, to achieve white color. In this case, the white pigment may be particles Y having an average particle diameter of less than 2.0. mu.m, as described later.
It should be noted that the transmission density OD of the polyester film 10 becomes lower than that of the polyester film substrate.
(polyester as a main component resin of each layer)
The layer constituting the polyester film substrate, for example, the base layer, the particle-containing layer a, the particle-containing layer B, and the other layers are preferably layers containing polyester as a main component resin.
Here, the "main component resin" refers to a resin having the largest content ratio of resin components constituting each layer.
The polyester may be obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic diol.
Examples of the aromatic dicarboxylic acid include terephthalic acid and 2, 6-naphthalenedicarboxylic acid, and examples of the other aliphatic diol include ethylene glycol, diethylene glycol, and 1, 4-cyclohexanedimethanol.
The polyester may be a homopolyester or a copolyester. Examples of the dicarboxylic acid component of the copolyester include one or more selected from isophthalic acid, phthalic acid, terephthalic acid, 2, 6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, hydroxycarboxylic acid, and the like, and examples of the other diol component include one or more selected from ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1, 4-cyclohexanedimethanol, neopentyl glycol, and the like. The third component contained is preferably isophthalic acid from the viewpoint of effectively imparting a matte feel.
The third component contained in the copolyester is preferably 30 mol% or less, more preferably 5 mol% or more or 30 mol% or less, further preferably 25 mol% or less, particularly preferably 7 mol% or more or 22 mol% or less. When the amount is within this range, the matte effect can be effectively imparted while maintaining the film forming stability.
As representative polyesters, polyethylene terephthalate (PET), polyethylene 2, 6-naphthalate (PEN), and the like can be exemplified.
(substrate layer)
The base layer of the polyester film base material is the thickest layer among the layers constituting the polyester film base material, and the composition thereof is arbitrary as long as the resin mainly composed of the above polyester is used.
The base material layer may include a layer containing particles, or may be composed only of a layer containing particles. Among them, from the viewpoint of cost, a layer containing no particles such as organic particles and inorganic particles described later is preferable.
From the viewpoint of preventing the curl of the present polyester film 10, the thickness of the base layer is preferably 60 to 99% of the thickness of the polyester film base material, more preferably 65% or more or 99% or less, and further preferably 70% or more or 99% or less. When the amount is within this range, the substrate layer itself has stiffness, and therefore, the curl of the present polyester film 10 is less likely to occur.
(particle-containing layer A)
The particle-containing layer a is a layer containing particles X having an average particle diameter of 2.0 μm or more, and a release layer described later is preferably provided on the surface thereof.
The average particle diameter of the particles X contained in the particle-containing layer a is preferably 2.0 μm or more.
The particle-containing layer a can roughen the surface of the particle-containing layer a by containing the particles X having an average particle diameter of 2.0 μm or more, and can form a matte tone. However, if the particle X is too large, the pressure rise of the filter in the polyester extrusion step in the production of a film becomes large, and there is a possibility that the productivity is lowered, and there is a possibility that the particle X is detached from the particle-containing layer a.
Thus, the average particle diameter of the particles X is preferably 2.0 μm or more, more preferably 10.0 μm or less, particularly 3.0 μm or more, or 9.0 μm or less, particularly 4.0 μm or more, or 8.0 μm or less.
When the particles X are powder particles, the average particle diameter can be determined as the particle diameter (d50) at 50% cumulative volume fraction in the spherical equivalent distribution of the powder by a centrifugal sedimentation type particle size distribution measuring apparatus (for example, SA-CP3, manufactured by Shimadzu corporation). The average particle diameter of the particles in the film or layer can be determined by measuring the diameter of 10 or more particles X observed by a Scanning Electron Microscope (SEM) and averaging the diameters. In this case, in the case of non-spherical particles, the average of the longest diameter and the shortest diameter can be measured as the diameter of each particle X. The same applies to particles Y described later.
The shape of the particles X is arbitrary. For example, the shape may be any of a sphere, a block, a rod, a plate, and the like. However, the spherical shape is preferable from the viewpoint of obtaining a uniform matte surface.
The hardness, specific gravity, color, and the like of the particles X are not particularly limited, and 2 or more different types may be used in combination.
The particles X having an average particle diameter of 2.0 μm or more are not particularly limited as long as they are particles capable of imparting a matte effect. For example, the particles may be inorganic particles, organic particles, or crosslinked polymer particles.
The inorganic particles may form voids in the film when the film is stretched, and are preferably inorganic particles from the viewpoint of not requiring the addition of a white pigment for improving visibility, and the organic particles are preferably organic particles in which voids are less likely to be formed, and therefore, are preferably organic particles in which the strength of the film is not reduced.
Examples of the inorganic particles include silica, calcium carbonate, kaolin, talc, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, lithium phosphate, calcium phosphate, magnesium phosphate, alumina, titanium oxide, zirconium oxide, lithium fluoride, calcium fluoride, lithium fluoride, zeolite, molybdenum sulfide, and the like.
The silica particles are prepared by removing Silica (SiO)2) In addition, for example, hydrous silicon dioxide or the like may be contained.
Examples of the organic particles include acrylic resins, styrene resins, urea resins, phenol resins, epoxy resins, and benzoguanamine resins.
Among them, particles made of a resin containing methyl methacrylate, styrene or both as a copolymerization component are particularly preferable because they have good compatibility with the PET film.
Examples of the crosslinked polymer particles include homopolymers or copolymers of vinyl monomers of divinylbenzene, styrene, acrylic acid, methacrylic acid, acrylic acid, or methacrylic acid. Furthermore, crosslinkable polymer particles such as polytetrafluoroethylene, benzoguanamine resin, thermosetting epoxy resin, unsaturated polyester resin, thermosetting urea resin, thermosetting phenol resin, and the like can also be used.
The content of the particles X in the particle-containing layer a is preferably 0.1 to 20% by mass, more preferably 1% by mass or more or 18% by mass or less, further preferably 2% by mass or more or 15% by mass or less, further preferably 3% by mass or more or 10% by mass or less, from the viewpoint of suitably roughening the surface of the particle-containing layer a and preventing the occurrence of breakage or the like during film stretching.
The particle-containing layer a may contain particles Y described later.
The thickness of the particle-containing layer A is preferably 1.0 to 20 μm, more preferably 2.0 μm or more and 20 μm or less, particularly 3.0 μm or more and 20 μm or less, particularly 4.0 μm or more and 15 μm or less.
When the thickness of the particle-containing layer a is 1.0 μm or more, a matte feeling can be effectively imparted. In addition, if the thickness of the particle-containing layer a exceeds 20 μm, the effect of improving matte feeling is lowered, and roughening of the film surface derived from the particles X may be reduced.
Regarding the relationship between the thickness of the particle-containing layer a and the average particle diameter of the particles X, (the average particle diameter of the particles X)/(the thickness of the particle-containing layer a) is preferably 0.1 to 5.0, more preferably 0.3 to 4.0, and particularly preferably 0.5 to 3.0, from the viewpoint of roughening of the film surface and suppressing falling-off of the particles.
(particle-containing layer B)
As described above, the particle-containing layer a may be provided on one surface side of the base material layer, and the particle-containing layer B different from the particle-containing layer a may be formed on the other surface side of the base material layer. The release layer described later need not be provided on the surface of the particle-containing layer B, but the provision of the release layer is not excluded.
In order to prevent curling of the entire polyester film 10, it is preferable that the particle-containing layer B also contains particles X having an average particle diameter of 2.0 μm or more.
However, the surface of the particle-containing layer B does not need to be roughened as in the case of the surface of the particle-containing layer a, because the surface can be roughened to an extent that the handling properties are suitable. Thus, the content of the particles X having an average particle diameter of 2.0 μm or more is less than that of the particle-containing layer A. When the content of the particles X having an average particle diameter of 2.0 μm or more in the particle-containing layer B is less than that in the particle-containing layer a, curling of the entire polyester film 10 can be prevented and a matte feeling can be imparted to the surface of the object on the front surface side of the particle-containing layer a, while a desired layer can be easily laminated on the surface of the particle-containing layer B.
Specifically, the content (mass%) of the particles X contained in the particle-containing layer B is preferably 0.1 to 100%, more preferably 1% or more or 95% or less, still more preferably 5% or more or 90% or less, still more preferably 10% or more or 80% or less, and still more preferably 60% or less, of the content (mass%) of the particles X contained in the particle-containing layer a.
The particle-containing layer B may contain particles Y having an average particle diameter of less than 2.0 μm in order to whiten the present polyester film 10.
In this case, the particle-containing layer B may contain the particles Y without containing the particles X, or may contain both the particles X and the particles Y.
In the case of containing both the particles X and the particles Y, the content mass ratio of the particles X to the particles Y is preferably 1: 99-99: 1, wherein 10: 90-90: 10. wherein 15: 85-85: 15.
the shape of the particles Y is arbitrary. For example, the shape may be any of a sphere, a block, a rod, a plate, and the like. However, from the viewpoint of being less likely to cause coarse protrusions due to aggregation, the spherical shape is preferred.
The hardness, specific gravity, color, and the like of the particles Y are not particularly limited, and 2 or more different types may be used in combination.
From the viewpoint of imparting white opacity due to a light scattering effect, the average particle diameter of the particles Y is preferably 0.05 μm to 0.50 μm, more preferably 0.10 μm or more or 0.45 μm or less, further preferably 0.20 μm or more or 0.40 μm or less, further preferably 0.25 μm or more.
The particles Y are preferably metal compound particles from the viewpoint of imparting white opacity due to a light scattering effect.
Examples of the metal compound particles include titanium oxide, calcium carbonate, barium sulfate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, alumina, and zirconia, and among them, metal compound particles such as titanium oxide, calcium carbonate, and barium sulfate are mentioned.
In the particle-containing layer B, when the particles corresponding to the particles X and the particles corresponding to the particles Y are the same material, the raw material is particles having different average particle diameters, but if mixed (blended), the particles are 1 type of particles having an average particle diameter among them. In such a case, the particle X or the particle Y is identified from the average particle diameter after mixing.
From the viewpoint of preventing curling of the present polyester film 10, the thickness of the particle-containing layer B is preferably in the same range as the thickness of the particle-containing layer a. From the above viewpoint, the thickness of the particle-containing layer B is also preferably 1.0 to 20 μm, and more preferably 2.0 μm or more or 18 μm or less, particularly 3.0 μm or more or 17 μm or less, and particularly preferably 4.0 μm or more or 15 μm or less.
The ratio of the thicknesses of the particle-containing layer a and the particle-containing layer B is preferably 0.1 or more and 10 or less, more preferably 0.2 or more or 5.0 or less, and particularly preferably 0.5 or more and 2.0 or less, from the viewpoint of preventing curling of the present polyester film 10.
(other Components)
Each layer constituting the polyester film substrate may be added with a conventionally known weather resistant agent, light blocking agent, antioxidant, heat stabilizer, lubricant, antistatic agent, fluorescent whitening agent, dye, pigment, and the like, as required. Further, an ultraviolet absorber, particularly a benzoxazinone-based ultraviolet absorber, may be contained according to the application.
< Release layer >
The polyester film 10 preferably has the following structure: a release layer is formed on the surface of the particle-containing layer A of the polyester film base.
The releasing layer preferably has a crosslinked structure derived from a crosslinking agent. Such a crosslinked structure can provide excellent hardness, and therefore, the present polyester film 10 can be sufficiently durable when it is pressure-bonded to an object.
From the viewpoint of having releasability and not smoothing (not lowering) the roughness of the surface of the polyester film substrate, the thickness of the release layer is preferably 0.001 to 1 μm, more preferably 0.002 μm or more or 0.5 μm or less, further preferably 0.005 μm or more or 0.2 μm or less, further preferably 0.008 μm or more or 0.15 μm or less, further preferably 0.01 μm or more or 0.1 μm or less, particularly preferably 0.01 μm or more or 0.08 μm or less.
The thickness of the release layer is preferably 0.1 to 100%, 0.2% or more or 50% or less, or 1.0% or more or 25% or less of the average surface roughness (Ra) of the surface of the release layer.
(formation of Release layer)
The release layer is preferably formed on the surface of the particle-containing layer a, i.e., the roughened surface, as an extremely thin film, and is therefore preferably formed by a coating-stretching method (in-line coating). But is not limited to this method.
As the coating-stretching method, for example, it is preferable to perform a treatment of coating the surface of the particle-containing layer a with a "release layer-forming composition" during sequential biaxial stretching, particularly before stretching in the 2 nd step after stretching in the 1 st step is completed. In this way, coating can be performed simultaneously with stretching, and the thickness of the release layer can be made thin according to the stretching magnification, and a suitable film can be produced as a polyester film.
As a method of applying a coating liquid containing the release layer forming composition, for example, there can be used: air knife coating, blade coating, rod coating, bar coating, blade coating, press coating, impregnation coating, reverse roll coating, transfer roll coating, gravure coating, contact roll coating, cast coating, spray coating, curtain coating, calender coating, extrusion coating, and other known coating methods.
More specifically, for example, a method of forming a polyester film by coating a coating liquid containing a release layer forming composition on a uniaxially stretched film stretched in the longitudinal direction (longitudinal direction) and then stretching the film in the transverse direction is excellent in sequential biaxial stretching. According to the above method, the film formation of the polyester film and the formation of the release layer can be performed simultaneously, and therefore, there is an advantage in production cost, and further, since the release layer is stretched after the coating, the thickness of the release layer can be changed depending on the stretch ratio, and the film coating can be performed more easily than the off-line coating.
Further, by providing a release layer on the polyester film before stretching, the release layer can be stretched together with the polyester film, whereby the release layer can be firmly adhered to the polyester film. Further, in the production of a biaxially stretched polyester film, the film is stretched while fixing the film ends with a jig or the like to confine the film in the machine direction and the transverse direction, and in the heat-fixing step, a high temperature can be applied while maintaining the flatness without generating wrinkles or the like.
Therefore, the heat treatment after coating can form a high temperature which cannot be achieved by other methods, and therefore, the film formability of the release layer is improved, the release layer and the polyester film can be more firmly adhered, and further, a firm release layer can be formed.
In addition, the release layer can be formed by off-line coating or on-line coating, and if necessary, heat treatment and irradiation with active energy rays such as ultraviolet irradiation can be used in combination. In order to improve the coatability and adhesiveness of the coating liquid for forming the release layer to the polyester film, the polyester film may be subjected to surface treatment such as chemical treatment, corona discharge treatment, plasma treatment, ozone treatment, chemical treatment, and solvent treatment before coating.
The release layer-forming composition, i.e., the coating liquid, may be a resin composition containing a release agent and a binder.
The "release agent" to be blended in the above release layer-forming composition is not particularly limited, and conventionally known release agents can be used. Examples thereof include compounds containing a long-chain alkyl group, fluorine compounds, organosilicon compounds, and waxes.
Among them, a long chain alkyl group-containing compound and a wax are preferable from the viewpoint of reducing the possibility of contamination even when used for optical applications, and a wax is preferable from the viewpoint of not significantly reducing the releasability even when heated.
Examples of the wax include natural waxes, synthetic waxes, and modified waxes.
The natural wax includes vegetable wax, animal wax, mineral wax, and petroleum wax.
Examples of the vegetable wax include candelilla wax, carnauba wax, rice bran wax, wood wax, jojoba oil, and the like.
Examples of the animal-based wax include beeswax, lanolin, and spermaceti wax. Examples of mineral waxes include montan wax, ozokerite (ozokerite), and purified ozokerite.
Examples of the petroleum wax include paraffin wax, microcrystalline wax, and vaseline.
Examples of the synthetic wax include synthetic hydrocarbons, modified waxes, hydrogenated waxes, fatty acids, amides, amines, imides, esters, ketones, Fischer-Tropsch wax (also referred to as an azole wax), and polyethylene wax. Further, the following polymers as a relatively low molecular weight polymer (specifically, a polymer having a number average molecular weight of 500 to 20000) are exemplified, that is, polypropylene, an ethylene-acrylic acid copolymer, polyethylene glycol, polypropylene glycol, and a block or graft conjugate of polyethylene glycol and polypropylene glycol.
Examples of the modified wax include montan wax derivatives, paraffin wax derivatives, and microcrystalline wax derivatives. The derivative herein refers to a compound obtained by any treatment of purification, oxidation, esterification, saponification, or a combination thereof. Hydrogenated castor oil and hydrogenated castor oil derivatives are examples of hydrogenated waxes.
Among them, from the viewpoint of stability of properties such as blocking, synthetic waxes are preferable as the release agent in the release layer, and among them, polyethylene waxes, and further oxidized polyethylene waxes are more preferable.
The number average molecular weight of the synthetic wax is usually 500 to 30000, preferably 1000 to 15000, and more preferably 2000 to 8000, from the viewpoint of stability of properties such as blocking and workability.
In addition, when the release layer is formed, it is preferable that the melting point or softening point of the wax is 80 ℃ or higher, particularly 110 ℃ or higher, in view of heating for crosslinking or the like. The upper limit of the melting point or softening point of the wax is not particularly limited, but is usually 300 ℃ or lower.
The ratio of the release agent in the release layer-forming composition is preferably 1 to 50% by mass in the nonvolatile component, and more preferably 5% by mass or more or 40% by mass or less, and further preferably 10% by mass or more or 30% by mass or less.
When the ratio of the release agent in the release layer-forming composition is in the above range, the strength of the coating film can be improved while maintaining good releasability.
The release layer-forming composition preferably contains a crosslinking agent in order to increase the strength of the release layer and to improve wettability. When the releasing layer-forming composition contains a crosslinking agent, the releasing layer after formation has a crosslinked structure derived from the crosslinking agent.
In addition, the release layer-forming composition preferably contains a binder in order to increase the strength of the release layer and further to improve the adhesion between the polyester film base and the release layer.
As the crosslinking agent, conventionally known materials can be used. Examples thereof include oxazoline compounds, isocyanate compounds, epoxy compounds, melamine compounds, carbodiimide compounds, silane coupling compounds, hydrazide compounds, aziridine compounds, and the like. Among them, oxazoline compounds, isocyanate compounds, epoxy compounds, melamine compounds, carbodiimide compounds and silane coupling compounds are preferable. In order to further enhance the strength of the release layer, a melamine compound and an oxazoline compound are preferable, and in order to improve the adhesion between the substrate and the film, an oxazoline compound, an isocyanate compound, an epoxy compound and a carbodiimide compound are preferable, and an oxazoline compound and an isocyanate compound are particularly preferable.
Specific examples of the binder include acrylic resins, polyvinyl compounds (polyvinyl alcohol, vinyl chloride-vinyl acetate copolymer, etc.), polyester resins, polyurethane resins, polyalkylene glycols, polyalkylene imines, methyl cellulose, hydroxy cellulose, and starches. Among them, a polyester resin is preferable from the viewpoint of improving the adhesion between the polyester film base and the release layer.
The acrylic resin is a polymer formed from a polymerizable monomer including an acrylic monomer and a methacrylic monomer. These may be homopolymers or copolymers, and further may be copolymers with polymerizable monomers other than acrylic or methacrylic monomers. In addition, copolymers of these polymers with other polymers (e.g., polyesters, polyurethanes, etc.) are also included. For example, block copolymers and graft copolymers. Or, further comprising: a polymer (in some cases, a mixture of polymers) obtained by polymerizing a polymerizable monomer in a polyester solution or a polyester dispersion. Also includes: a polymer (in some cases, a mixture of polymers) obtained by polymerizing a polymerizable monomer in a polyurethane solution or a polyurethane dispersion. Also includes: a polymer (polymer mixture in some cases) obtained by polymerizing a polymerizable monomer in another polymer solution or dispersion. In addition, in order to further improve the adhesion with the substrate, can also contain hydroxyl, amino.
The polymerizable monomer is not particularly limited, and examples of the particularly representative compound include: various carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, and citraconic acid, and salts thereof; various hydroxyl group-containing monomers such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, monobutyl hydroxyfumarate, and monobutyl hydroxyitaconate; various (meth) acrylic acid esters such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and lauryl (meth) acrylate; various nitrogen-containing compounds such as (meth) acrylamide, diacetone acrylamide, N-methylolacrylamide, and (meth) acrylonitrile; various styrene derivatives such as styrene, α -methylstyrene, divinylbenzene and vinyltoluene, and various vinyl esters such as vinyl propionate; various silicon-containing polymerizable monomers such as γ -methacryloxypropyltrimethoxysilane and vinyltrimethoxysilane; phosphorus-containing vinyl monomers; various halogenated alkenes such as vinyl chloride and vinylidene chloride; various conjugated dienes such as butadiene.
When the acrylic resin contains a hydroxyl group, the hydroxyl value of the acrylic resin is preferably 2 to 100mgKOH/g, more preferably 5 to 50 mgKOH/g. When the hydroxyl value falls within the above range, the coating appearance and transparency are optimized.
The polyvinyl alcohol refers to a compound having a polyvinyl alcohol moiety, and for example, further includes: as the modified compound obtained by partially acetalizing or butyralization of polyvinyl alcohol, conventionally known polyvinyl alcohol can be used. The polymerization degree of the polyvinyl alcohol is not particularly limited, but is usually 100 or more, preferably 300 to 40000. When the polymerization degree is less than 100, the water resistance of the release layer may be lowered. The saponification degree of polyvinyl alcohol is not particularly limited, and practically, a saponified polyvinyl acetate having a saponification degree of usually 70 mol% or more, preferably in the range of 70 to 99.9 mol%, more preferably 80 to 97 mol%, and particularly preferably 86 to 95 mol% is used.
Examples of the polyester resin include those comprising, as main components, the following polycarboxylic acids and polyhydric hydroxyl compounds. That is, as the polycarboxylic acid, there can be used: terephthalic acid, isophthalic acid, phthalic acid, 4' -diphenyldicarboxylic acid, 2, 5-naphthalenedicarboxylic acid, 1, 5-naphthalenedicarboxylic acid and 2, 6-naphthalenedicarboxylic acid, 2, 7-naphthalenedicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid, potassium 2-sulfonate terephthalate, 5-sodium sulfonate isophthalate, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutaric acid, succinic acid, trimellitic acid, trimesic acid, pyromellitic acid, trimellitic anhydride, phthalic anhydride, p-hydroxybenzoic acid, monopotassium trimellitate, and ester-forming derivatives thereof, and the like can be used as the polyhydric hydroxyl compound: ethylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 4-butanediol, 1, 6-hexanediol, 2-methyl-1, 5-pentanediol, neopentyl glycol, 1, 4-cyclohexanedimethanol, terephthalyl alcohol, bisphenol a-ethylene glycol adduct, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, dimethylolpropionic acid, glycerol, trimethylolpropane, sodium dimethylolethylsulfonate, potassium dimethylolpropionate, and the like. From these compounds, 1 or more species can be appropriately selected, and a polyester resin can be synthesized by a polycondensation reaction by a conventional method.
The polyurethane resin is a polymer compound having a urethane bond in a molecule. Typically polyurethane resins are made by the reaction of a polyol with an isocyanate. Examples of the polyol include polycarbonate polyols, polyester polyols, polyether polyols, polyolefin polyols, and acrylic polyols, and these compounds may be used alone or in combination of two or more.
The polycarbonate polyol is obtained by dealcoholizing a polyol and a carbonate compound. Examples of the polyhydric alcohol include ethylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 4-cyclohexanediol, 1, 4-cyclohexanedimethanol, 1, 7-heptanediol, 1, 8-octanediol, 1, 9-nonanediol, 1, 10-decanediol, neopentyl glycol, 3-methyl-1, 5-pentanediol, and 3, 3-dimethylolheptane. Examples of the carbonate compound include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, and ethylene carbonate, and examples of the polycarbonate polyol obtained by the reaction of these include poly (1, 6-hexylene) carbonate and poly (3-methyl-1, 5-pentylene) carbonate.
Examples of the polyester polyol include: prepared from polycarboxylic acids (malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, fumaric acid, maleic acid, terephthalic acid, isophthalic acid, etc.) or their anhydrides and polyhydric alcohols (ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butylene glycol, 1, 3-butylene glycol, 1, 4-butylene glycol, 2, 3-butylene glycol, 2-methyl-1, 3-propanediol, 1, 5-pentanediol, neopentyl glycol, 1, 6-hexanediol, 3-methyl-1, 5-pentanediol, 2-methyl-2, 4-pentanediol, 2-methyl-2-propyl-1, 3-propanediol, 1, 8-octanediol, 2, 4-trimethyl-1, 3-pentanediol, 2-ethyl-1, 3-hexanediol, 2, 5-dimethyl-2, 5-hexanediol, 1, 9-nonanediol, 2-methyl-1, 8-octanediol, 2-butyl-2-ethyl-1, 3-propanediol, 2-butyl-2-hexyl-1, 3-propanediol, cyclohexanediol, bishydroxymethylcyclohexane, dimethanolbenzene, bishydroxyethoxybenzene, alkyldialkanolamines, lactone diol, etc.).
Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polyethylenepropylene glycol, polytetramethylene ether glycol, and polyhexamethylene ether glycol.
Examples of the polyisocyanate compound used for obtaining the polyurethane resin include aromatic diisocyanates such as toluene diisocyanate, xylene diisocyanate, methylene diphenyl diisocyanate, benzene diisocyanate, naphthalene diisocyanate and tolidine diisocyanate, aliphatic diisocyanates having an aromatic ring such as α, α, α ', α' -tetramethylxylene diisocyanate, methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate and hexamethylene diisocyanate, and alicyclic diisocyanates such as cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate and isopropylidene dicyclohexyl diisocyanate. These may be used alone or in combination of two or more.
A chain extender may be used in synthesizing the polyurethane resin, and the chain extender is not particularly limited as long as it has 2 or more reactive groups that react with isocyanate groups, and in general, a chain extender having 2 hydroxyl groups or amino groups may be mainly used.
Examples of the chain extender having 2 hydroxyl groups include glycols such as aliphatic glycols such as ethylene glycol, propylene glycol and butanediol, aromatic glycols such as benzenedimethanol and bishydroxyethoxybenzene, and ester glycols such as neopentyl glycol hydroxypivalate. In addition, as the chain extender having 2 amino groups, examples thereof include aromatic diamines such as tolylenediamine, xylylenediamine and diphenylmethanediamine, aliphatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, 2-dimethyl-1, 3-propanediamine, 2-methyl-1, 5-pentanediamine, trimethylhexamethylenediamine, 2-butyl-2-ethyl-1, 5-pentanediamine, 1, 8-octanediamine, 1, 9-nonanediamine and 1, 10-decanediamine, and alicyclic diamines such as 1-amino-3-aminomethyl-3, 5, 5-trimethylcyclohexane, dicyclohexylmethanediamine, isopropylidene-cyclohexyl-4, 4' -diamine, 1, 4-diaminocyclohexane and 1, 3-bisaminomethylcyclohexane.
The polyurethane resin in the present invention may be a solvent medium, and preferably water medium. In order to disperse or dissolve the polyurethane resin in water, there are: forced emulsification type using an emulsifier, self-emulsification type in which a hydrophilic group is introduced into a urethane resin, or water-soluble type. In particular, a self-emulsifying type in which an ionic group is introduced into the structure of a polyurethane resin and the polyurethane resin is ionomerized is preferable because it is excellent in storage stability of a liquid and water resistance and transparency of the obtained release layer.
Examples of the ionic group to be introduced include various groups such as a carboxyl group, a sulfonic acid, a phosphoric acid, a phosphonic acid, and a quaternary ammonium salt, and a carboxyl group is preferable. As a method for introducing a carboxyl group into a polyurethane resin, various methods can be adopted in each stage of the polymerization reaction.
For example, the following methods are available: a method of using a resin having a carboxyl group as a copolymerization component in synthesizing the prepolymer; a method of using a component having a carboxyl group as one component such as a polyol, a polyisocyanate, a chain extender, etc. Particularly, a method of introducing a desired amount of carboxyl group in accordance with the amount of the component to be charged, using a carboxyl group-containing diol, is preferable. For example, dimethylolpropionic acid, dimethylolbutyric acid, bis- (2-hydroxyethyl) propionic acid, bis- (2-hydroxyethyl) butyric acid, and the like may be copolymerized with the diol used for the polymerization of the polyurethane resin. The carboxyl group is preferably in the form of a salt neutralized with ammonia, an amine, an alkali metal, an inorganic base, or the like. Particularly preferred are ammonia, trimethylamine, and triethylamine. The urethane resin can use a carboxyl group, which is removed from a neutralizer in a drying step after coating, as a crosslinking reaction site by another crosslinking agent. This provides excellent stability in the liquid state before coating, and further improves the durability, solvent resistance, water resistance, blocking resistance, and the like of the obtained release layer.
The ratio of the binder in the release layer-forming composition is preferably 20 to 70% by mass of the nonvolatile component, and more preferably 30% by mass or more or 65% by mass or less, and further preferably 40% by mass or more or 60% by mass or less.
The ratio of the crosslinking agent is preferably 10 to 70% by mass in the nonvolatile component, and more preferably 15% by mass or more or 60% by mass or less, and further preferably 20% by mass or more or 40% by mass or less.
The coating liquid containing the release layer forming composition may be an aqueous coating liquid containing water as a solvent, or may be a coating liquid containing an organic solvent as a main component, and is preferably an aqueous coating liquid.
The aqueous coating solution may contain a small amount of an organic solvent.
Examples of the organic solvent include alcohols such as ethanol, isopropanol, ethylene glycol, and glycerol; ethers such as ethyl cellosolve, t-butyl cellosolve, propylene glycol monomethyl ether, and tetrahydrofuran; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate; amines such as methylethanolamine, and the like. These may be used alone or in combination of two or more. These organic solvents are appropriately selected and contained in the aqueous coating solution as needed, and the stability and coatability of the coating solution can be improved.
The release layer-forming composition may contain particles as necessary for improving blocking and sliding properties. Further, the functional layer may contain an antifoaming agent, a coating property improving agent, a thickener, an organic lubricant, an ultraviolet absorber, an antioxidant, a foaming agent, and the like.
< the present polyester film 10 >
(thickness)
The thickness of the present polyester film 10 is not particularly limited as long as it can be formed into a film. Among them, from the viewpoint of mechanical strength, workability, productivity, etc., it is preferably from 1 μm to 300. mu.m, and more preferably from 5 μm to 125 μm, and further more preferably from 8 μm to 100 μm.
(Transmission concentration OD value)
The polyester film 10 preferably has a transmission concentration OD of 0.10 or more.
A transmission density OD value of 0.10 or more means that the opacity is high, that is, the whiteness is high.
From the above-mentioned viewpoints, the OD value of the transmittance of the polyester film 10 is more preferably 0.10 to 1.0, and still more preferably 0.15 or more or 0.90 or less, wherein 0.20 or more or 0.80 or less, wherein 0.25 or more, wherein 0.30 or more, wherein 0.50 or more.
When the transmission density OD value of the present polyester film 10 is in the above range, visibility, namely, visibility is good, and therefore, after the rough surface is transferred to the transfer object, the present polyester film 10 is easily peeled.
As a method for adjusting the transmission density OD value of the polyester film 10 to 0.10 or more, for example, the following known methods can be used: the polyester film base material or any layer contains white pigment; a material having a large difference in refractive index from the main component resin of the polyester film substrate is contained in the substrate or the particle-containing layer; stretching the film containing the fine particles so that voids are formed in the polyester film substrate; and the like.
When the white pigment, for example, the metal compound particles are contained to achieve white color, for example, the metal compound particles are contained in any one of the substrate layer, the particle-containing layer, and a layer provided on the opposite side of the substrate layer from the particle-containing layer, or 2 or more layers thereof, to achieve white color. In this case, the white pigment may be exemplified by the particles Y having an average particle diameter of less than 2.0. mu.m.
(surface roughness of film)
The average surface roughness (Ra) of the polyester film 10 is preferably 0.05 to 2.0. mu.m.
Here, the average surface roughness (Ra) of the present polyester film 10 refers to the surface thereof when a release layer is formed on one side of a polyester film base material, and refers to both surfaces thereof when release layers are formed on both sides of a polyester film base material.
When the average surface roughness (Ra) of the surface of the polyester film 10 is in the above range, a matte effect can be exhibited, and the surface can be pressed against an object by pressure and released from the object, thereby imparting the matte effect to the surface of the object.
From the above-mentioned viewpoints, the average surface roughness (Ra) of the polyester film 10 is preferably 0.05 to 2.0. mu.m, more preferably 0.1 to 1.0. mu.m, further preferably 0.2 to 0.9. mu.m.
The average surface roughness (Ra) of the polyester film 10 can be determined by using a surface roughness measuring instrument, for example, a surface roughness measuring instrument (SE-3500) manufactured by Okawa Kagaku K.K.
In order to make the average surface roughness (Ra) of the present polyester film 10 0.1 to 2.0 μm, for example, the particle-containing layer a may be provided so that the average surface roughness (Ra) of one surface or both surfaces of the polyester film base material is 0.1 to 2.0 μm and the thickness of the release layer is sufficiently thin relative to the average surface roughness (Ra). But is not limited to this method.
If one surface of the present polyester film 10 is made matte, the other surface is sufficiently roughened to a degree that does not interfere with handling, and thus the matte surface is not required.
Thus, the average surface roughness (Ra)1 of the surface on the particle-containing layer a side, i.e., the release layer side, of the polyester film base material may be 0.1 μm to 2.0 μm, and the average surface roughness (Ra)2 of the surface of the present polyester film 10 on the opposite side may be less than 0.1 μm. In this case, the ratio of (Ra)2 to (Ra)1 is preferably 0.01 to 100%, more preferably 0.1% or more, 1% or more, 3% or more, or 90% or less.
(gloss degree)
In the present polyester film 10, the gloss of at least the release layer-side surface is preferably 30% or less.
When the glossiness of the film surface is 30% or less, a matte tone having a high quality feeling can be formed. The lower limit is about 0.1%.
From the above-mentioned viewpoint, the gloss of at least the release layer-side surface of the present polyester film 10 is preferably 30% or less, more preferably 0.1% or more or 30% or less, further preferably 25% or less, further preferably 20% or less.
The gloss of the surface of the polyester film 10 on the side of the release layer can be measured by a gloss meter, and for example, the gloss can be measured by the method of JIS Z8741 using a gloss meter model VG2000 manufactured by Nippon Denshoku K.K.
In the present polyester film 10, in order to make the gloss of at least the release layer side surface 30% or less, the average surface roughness (Ra) of one surface or both surfaces of the polyester film base material is set to 0.05 μm to 2.0 μm, and the thickness of the release layer is sufficiently reduced with respect to the average surface roughness (Ra), thereby forming the film. But is not limited to this method.
(Release force of Release layer)
In the polyester film 10, the release force of the release layer is preferably 100 to 3500mN/cm, more preferably 500mN/cm or more, still more preferably 3000mN/cm or less, further preferably 1000mN/cm or more, or 2500mN/cm or less. By setting the above range, the peeling operation becomes easy. The value of the peeling force corresponds to "peeling force of the release layer before heating" described later.
The peeling force of the release layer before heating can be measured as follows: the pressure-sensitive adhesive tape (polyester adhesive tape "No. 31B" manufactured by Rido electric Co., Ltd.) was pressure-bonded to the surface of the release layer 1 time in a reciprocating manner by using a 2kg rubber roll, left standing at room temperature for 1 hour, and 180 ℃ peeled off from the surface of the release layer at a stretching speed of 300 mm/min by using "AGX-plus" manufactured by Shimadzu corporation.
The peeling force of the heated release layer is preferably 100 to 4500mN/cm, more preferably 500mN/cm or more, or 3900mN/cm or less, further preferably 1000mN/cm or more, or 3500mN/cm or less. By setting the above range, sufficient peeling can be performed even after heating.
The peeling force of the release layer after heating can be measured as follows: the surface of the release layer was heated in an oven at 100 ℃ for 1 hour with a 2kg rubber roll to which an adhesive tape (polyester adhesive tape "No. 31B" manufactured by Nindon electric Co., Ltd.) was pressure-bonded 1 time, and then allowed to stand at room temperature for 1 hour to measure the thickness. The peel force was determined as follows: the measurement was carried out by 180 ℃ peeling at a drawing speed of 300 mm/min using "AGX-plus" manufactured by Shimadzu corporation.
In addition, when the easiness of controlling the peeling force of the release layer before and after heating is taken into consideration, the peeling force before and after heating is compared, and the value of the difference between the peeling force before and after heating (peeling force after heating-peeling force before heating) is preferably 0 to 3000mN/cm, more preferably 0 to 2000mN/cm, and further preferably 0 to 1500 mN/cm.
< method for producing polyester film 1 or 10 >
An example of the method for producing the polyester film 10 will be described below. However, the method for producing the polyester film 10 is not limited to the method described below.
First, raw materials for each of the dried or undried layers, that is, each of the base layer, the particle-containing layer a, the particle-containing layer B, and further other layers are prepared by a known method, supplied to each melt extrusion device, heated to a temperature equal to or higher than the melting point of the polymer, and melted. The molten polymers of each layer are then introduced into a mold and laminated, typically via a manifold or feedblock.
Next, the molten sheet extruded from the die was quenched and solidified on a rotary cooling drum to a temperature equal to or lower than the glass transition temperature, thereby obtaining an unoriented sheet in a substantially amorphous state. In the above case, in order to improve the planarity of the sheet, it is preferable to improve the adhesion between the sheet and the rotary cooling drum, and it is preferable to use an electrostatic application method and/or a liquid coating method.
Next, the obtained unstretched sheet is stretched in one direction by a roller or tenter type stretching machine. The following methods may be mentioned: the stretching temperature is usually 70 to 150 ℃, preferably 80 to 140 ℃, and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Then, the sheet is stretched in a direction perpendicular to the stretching direction in the first step, usually at a temperature of 70 to 170 ℃ and a stretching ratio of usually 2.5 to 7 times, preferably 3.0 to 6 times. Then, heat treatment is carried out at a temperature of 180 to 270 ℃ under tension or under relaxation of 30% or less to obtain a biaxially oriented film. In the above stretching, a method of performing unidirectional stretching in 2 stages or more may be employed. In the above case, it is preferable to perform the final biaxial stretching magnifications so as to fall within the above ranges.
After the heat treatment step, it is preferable to perform 2 to 20% relaxation in the longitudinal direction and/or the transverse direction in the highest temperature zone of the heat treatment and/or the cooling zone at the heat treatment outlet. Further, if necessary, additional longitudinal stretching and additional transverse stretching may be added.
In the above production method, as the coating and stretching method, it is preferable that the "release layer-forming composition" is coated between the longitudinal stretching and the transverse stretching. In this way, coating can be performed simultaneously with stretching, and the thickness of the release layer can be made thin according to the stretching magnification, and a suitable film can be produced as a polyester film.
In the polyester film 1, the film thickness of the polyester film 10 may be referred to as the film thickness of the polyester film 1, the transmission density OD of the polyester film 10 may be referred to as the transmission density OD of the polyester film 1, and the average surface roughness (Ra) of the polyester film 10 may be referred to as the average surface roughness (Ra) of the polyester film 1.
The present polyester film 1 and the present polyester film 10 have roughened film surfaces and can transfer the surface state thereof to the surface of an object product, and therefore, can be used for surface shaping applications requiring matte finishing, and can be suitably used as a surface shaping film for an electromagnetic wave shielding member in particular.
< description of terms >
In the present specification, when "X to Y" (X, Y is an arbitrary number), the meaning of "X or more and Y or less" is included, and the meaning of "preferably more than X" or "preferably less than Y" is also included, unless otherwise specified.
In addition, the meaning of "preferably more than X" or "preferably less than Y" is also included in the case of "X or more" (X is an arbitrary number) or "Y or less" (Y is an arbitrary number).
Examples
Hereinafter, the present invention will be described in further detail based on the following examples and comparative examples.
First, the measurement method and evaluation method of various physical properties in the following examples and comparative examples will be described.
In the examples and comparative examples, "parts" means "parts by mass". The assay used in the present invention is as follows.
(1) Intrinsic viscosity of polyester
1g of polyester from which particles incompatible with the polyester were removed was precisely weighed, and 100ml of a mixed solvent of phenol/tetrachloroethane (mass ratio) 50/50 was added to dissolve the polyester, and the solution was measured at 30 ℃.
(2) Average particle diameter of the particles
The particle size was measured by the sedimentation method using a centrifugal sedimentation type particle size distribution measuring apparatus manufactured by Shimadzu corporation, model SA-CP 3. The value of 50% of the cumulative (volume basis) in the spherical equivalent distribution of the particles obtained by the measurement was used as the average particle diameter.
(3) Method for measuring average surface roughness (Ra)
The surface roughness was measured as follows using a surface roughness measuring instrument (SE-3500) manufactured by Xiaobanguo, K.K. That is, when a portion of the sampling length L (2.5mm) is extracted from the film cross-sectional curve along the direction of the average line, the average line of the extracted portion is taken as the x-axis, the direction of the vertical magnification is taken as the y-axis, and the roughness curve y ═ f (x) is expressed by the following equation, the value [ nm ] is expressed. The arithmetic mean roughness is as follows: the roughness curves were 10 lines obtained from the surface of the sample film, and the average value of the arithmetic average roughness of the extracted portion obtained from these roughness curves was used as a representation. The radius of the tip of the stylus was set to 2 μm, the load was set to 30mg, and the cutoff value was set to 0.08 mm.
Ra＝(1/L)∫L0|f(x)|dx
(4) Evaluation of gloss of polyester film
The gloss was measured by the method of JISZ8741 using a gloss meter model VG2000 manufactured by Nippon Denshoku K.K. The reflectance of the sample was determined as the glossiness based on the reflectance of the black standard plate at the incident angle and the reflection angle of 60 degrees.
(5) Film thickness of mold releasing layer
RuO for surface of mold release layer4And dyeing and embedding the dye in epoxy resin. Then, forRuO for slicing produced by ultra-thin slicing method4Staining was performed, and the cross section of the release layer was measured by a transmission electron microscope (H-7650 manufactured by Hitachi High-Technologies Corporation, acceleration voltage 100 kV).
(6) OD value of transmission concentration
The transmitted intensity of white light was measured according to JISK5600-4 using a Macbeth densitometer model TD-904. The measurement was performed at 5 points, and the average value was defined as the OD value. The larger the value, the lower the light transmittance.
(7) Peel force before heating
The pressure-sensitive adhesive tape (polyester pressure-sensitive adhesive tape "No. 31B" manufactured by Nindon electric Co., Ltd.) was pressure-bonded to the surface of the release layer 1 time in a reciprocating manner using a 2kg rubber roll, and the release force after leaving at room temperature for 1 hour was measured. The peel force was determined as follows: the resultant was peeled at 180 ℃ under a condition of a drawing speed of 300 mm/min by using "AGX-plus" manufactured by Shimadzu corporation, and the peel force at this time was measured.
(8) Post heat peel force
A pressure-sensitive adhesive tape (polyester tape "No. 31B" manufactured by Nidong electric Co., Ltd.) was pressure-bonded to the surface of the release layer 1 time in a reciprocating manner using a 2kg rubber roll, and then heated in an oven at 100 ℃ for 1 hour. Thereafter, the peel force after leaving at room temperature for 1 hour was measured. The peel force was performed as follows: using "AGX-plus" manufactured by Shimadzu, 180 ℃ peeling was performed at a drawing speed of 300 mm/min.
(9) Evaluation of Heat resistance of Release layer
The peel force measured in (7) and (8) above was used as a difference in heat peel force (peel force after heating-peel force before heating), and the difference in heat peel force was calculated.
(10) Evaluation of Strength of Release layer
After the surface of the release layer was reciprocated 10 times by a brush-polishing tester and a special felt manufactured by the taiping physico-chemical industry, the felt was observed, and the case where no white powder was observed was rated as "good", the case where very little white powder was observed was rated as "Δ (good), the case where a little white powder was observed was rated as" Δ (usual "), and the case where white powder was observed over the entire surface was rated as" x (port ").
(11) Evaluation of crimpability
A polyester film (sample) stored for 24 hours at room temperature in a state of a film roll was cut into 150 mm. times.150 mm to obtain a measurement sample piece. The test piece was placed on a glass plate, and the four corners of the test piece were lifted from the glass plate, and the curl property was evaluated by the following criteria.
Very good (verygood): the average value of the four corners floating is more than 0mm and less than 6mm
Good (good): the average value of the four corners floating is more than 6mm and less than 10mm
Δ (usual): the average value of the four corners floating is more than 10mm and less than 30mm
X (por): the average value of the four corners floating is more than 30mm
The polyesters used in examples and comparative examples were prepared as follows.
< polyester (A) >
Polyethylene terephthalate homopolymer (intrinsic viscosity 0.65dl/g)
< polyester (B) >
Polyethylene terephthalate homopolymer containing 10% by mass of crosslinked organic particles of an alkyl methacrylate-styrene copolymer having an average particle diameter of 4.5 μm
< polyester (C) >
Copolymerized ethylene terephthalate obtained by copolymerizing 22 mol% of isophthalic acid as a dicarboxylic acid component
< polyester (D) >
Polyethylene terephthalate homopolymer containing 15 mass% of silica particles having an average particle diameter of 4.0 μm
< polyester (E) >
Polyethylene terephthalate homopolymer containing 15 mass% of silica particles having an average particle diameter of 1.5 μm
< polyester (F) >
Polyethylene terephthalate homopolymer containing 50 mass% of titanium oxide particles having an average particle diameter of 0.3 μm
The compound used for forming the release layer is as follows.
< wax emulsion (IA) >
300g of oxidized polyethylene wax having a melting point of 140 ℃, 650g of ion exchange water, 50g of decaglycerol monooleate surfactant and 10g of 48% potassium hydroxide aqueous solution were charged into an emulsifying apparatus having an internal volume of 1.5L equipped with a stirrer, a thermometer and a temperature controller, and after replacement with nitrogen gas, the mixture was sealed, stirred at a high speed of 150 ℃ for 1 hour, cooled to 130 ℃ and passed through a high-pressure homogenizer under 400 atmospheres, and cooled to 40 ℃ to obtain a wax emulsion (IA).
< wax emulsion (IB) >
Wax emulsion (IB) was obtained by the same method as the method for producing wax emulsion (IA) except that paraffin having a melting point of 60 ℃ was used in the method for producing wax emulsion (IA).
< Long-chain alkyl Compound (IC) >)
In a four-necked flask, 200 parts of xylene and 600 parts of octadecyl isocyanate were charged and heated with stirring. From the time point when xylene started to reflux, 100 parts of polyvinyl alcohol having an average degree of polymerization of 500 and a degree of saponification of 88 mol% were added little by little at 10 minute intervals over about 2 hours. After the addition of polyvinyl alcohol was completed, the reaction was refluxed for 2 hours. After cooling the reaction mixture to about 80 ℃, it was added to methanol, so that the reaction product precipitated as a white precipitate, and therefore, the precipitate was filtered off, 140 parts of xylene was added, heated to completely dissolve it, and then methanol was added again to precipitate it, and this operation was repeated a plurality of times, and then the precipitate was washed with methanol, dried and pulverized to obtain a long-chain alkyl compound (IC).
< fluorine Compound (ID) >
In a reaction vessel made of glass, CF as an acrylate containing perfluoroalkyl group is placed3(CF2)nCH2CH2OCOCH＝CH2(n is 5 to 11, and the average of n is 9)80.0g, acetoacetoxyethyl methacrylate 20.0g, dodecanethiol 0.8g, deoxidized pure water 354.7g, acetone 40.0g, and C16H33N(CH3)3Cl1.0g and C8H17C6H4O(CH2CH2O)nH (n ═ 8)3.0g, azobisisobutylamidine dihydrochloride 0 was added5g, copolymerization was carried out at 60 ℃ for 10 hours while stirring under a nitrogen atmosphere, to obtain a copolymer emulsion (ID) of a fluorine compound.
< Melamine Compound (IIA) >
Hexamethoxymethylolmelamine
< isocyanate-based Compound (IIB) >
1000 parts of hexamethylene diisocyanate was stirred at 60 ℃ and 0.1 part of ammonium tetramethyloctoate was added as a catalyst. After 4 hours, 0.2 part of phosphoric acid was added to stop the reaction, thereby obtaining an isocyanurate type polyisocyanate composition. 100 parts of the obtained isocyanurate type polyisocyanate composition, 42.3 parts of methoxypolyethylene glycol having a number average molecular weight of 400, and 29.5 parts of propylene glycol monomethyl ether acetate were charged and the mixture was held at 80 ℃ for 7 hours. Thereafter, 35.8 parts of methyl isobutyrylacetate, 32.2 parts of diethyl malonate, and 0.88 part of a 28% methanol solution of sodium methoxide were added while maintaining the temperature of the reaction solution at 60 ℃ for 4 hours. 58.9 parts of n-butanol was added, the reaction solution was kept at 80 ℃ for 2 hours, and then 0.86 part of 2-ethylhexyl acid phosphate was added to obtain an isocyanate compound (IIB) as a blocked polyisocyanate.
< polyester resin (III) >
An aqueous dispersion of a polyester resin obtained by copolymerization of (acid component) terephthalic acid/isophthalic acid 5-sodium sulfonate// (diol component) ethylene glycol/1, 4-butanediol/diethylene glycol (56/40/4// 70/20/10 (mol%).
[ example 1]
Raw materials in which polyesters (B) and (C) were mixed in a mass ratio of 80% and 20% respectively were used as a raw material of the a layer (particle-containing layer a), polyester (a) was used as a raw material of the base layer, raw materials in which polyesters (a), (E) and (F) were mixed in a mass ratio of 70%, 15% and 15% respectively were used as a raw material of the B layer (particle-containing layer B), each of the raw materials was fed to 3 extruders, melted at 285 ℃ respectively, and then co-extruded on a cooling roll set at 35 ℃ in 3 layer configurations of 3 layers (discharge amount of a layer/base layer/B layer: 5: 40: 5), and cooled and solidified to obtain an unstretched sheet. Next, after stretching 3.0 times in the longitudinal direction at a film temperature of 85 ℃ by a difference in the peripheral speed of the rolls, a coating solution 1 shown in the following table 1 was applied to the surface of the a layer of the longitudinally stretched film, introduced into a tenter, stretched 4.1 times in the transverse direction at 95 ℃, and subjected to a heat treatment at 235 ℃, followed by 2% relaxation in the transverse direction, to obtain a polyester film (sample) having a release layer with a thickness of 0.03 μm after drying on the a layer side of a polyester film base material with a thickness of 50 μm (a layer/base layer/B layer: 5 μm/40 μm/5 μm) and an average surface roughness (Ra) on the release layer side of 0.6 μm.
The properties of the polyester film (sample) are shown in table 2 below.
[ examples 2 to 12]
A polyester film (sample) was produced in the same manner as in example 1, except that the composition of the coating liquid was changed to the composition shown in table 1. The properties of the obtained polyester film (sample) are shown in table 2.
The polyester film (sample) of any of the examples was excellent in both the average surface roughness (Ra) and the gloss, and also in the peel force before and after heating and the strength of the release layer.
[ example 13]
A polyester film (sample) having a release layer having a film thickness of 0.03 μm after drying on the a layer side of a polyester film base material having a thickness of 50 μm (a layer/base layer/B layer: 5 μm/40 μm/5 μm) and an average surface roughness (Ra) on the release layer side of 0.6 μm was obtained in the same manner as in example 1 except that a raw material in which polyesters (a), (B), (C) and (F) were mixed at mass ratios of 65%, 10% and 15% was used as a raw material for the B layer (particle-containing layer B) and that the coating solution 5 shown in table 1 below was applied instead of the coating solution 1.
The properties of the polyester film (sample) are shown in table 3 below.
[ example 14]
A release sheet having a thickness of 0.03 μm after drying on the a layer side of a polyester film base material having a thickness of 50 μm (a layer/base material layer/B layer: 5 μm/40 μm/5 μm) was obtained in the same manner as in example 1 except that a release layer having a thickness of 0.03 μm after drying was formed on the a layer side of the polyester film base material, and a release layer having a thickness of 0.03 μm was formed on the release layer side of the polyester film base material, in which the raw material of the a layer (particle-containing layer a) was mixed at a mass ratio of 65% and 35%, the raw material of the polyester (a) was used as the raw material of the base layer, and the raw material of the mixed raw material of the polyesters (a) and (E) was used as the raw material of the base material layer, and the raw material of the mixed raw material of the polyesters (a) and (E) was used as the raw material of the mixed material of the base material of the polyester (a) and the mixed raw material of the polyesters (a), And the release layer side surface had an average surface roughness (Ra) of 0.4. mu.m (sample).
The properties of the polyester film (sample) are shown in table 2 below.
[ examples 15 to 25]
A polyester film (sample) was produced in the same manner as in example 14, except that the composition of the coating liquid was changed to the composition shown in table 1. The properties of the obtained polyester film (sample) are shown in table 2.
The polyester film (sample) of any of the examples was excellent in both the average surface roughness (Ra) and the gloss, and also in the peel force before and after heating and the strength of the release layer.
Comparative example 3
A polyester film (sample) having a release layer having a film thickness of 0.03 μm after drying and an average surface roughness (Ra) of the release layer side surface of 0.2 μm on the a layer side of a polyester film base material having a thickness of 50 μm (a layer/base material layer/B layer: 5 μm/40 μm/5 μm) was obtained in the same manner as in example 14, except that a raw material in which polyesters (a) and (E) were mixed in a mass ratio of 65% and 35% respectively was used as a raw material of the a layer (particle-containing layer a), and the polyester (a) was used as a raw material of the base material layer, and a coating solution 5 shown in table 1 was applied instead of the coating solution 1.
The properties of the polyester film (sample) are shown in tables 2 and 3 below, and the film had high glossiness and poor visibility.
Comparative example 4
The raw materials in which the polyesters (A) and (B) were mixed at mass ratios of 20% and 80% respectively were used as the raw material for the layer A (particle-containing layer A), the raw materials in which the polyesters (A), (B) and (F) were mixed at mass ratios of 90%, 8% and 2% respectively were used as the raw material for the layer B (particle-containing layer B), each of them was fed to 2 extruders and melted at 285 ℃ respectively, on a cooling roll set at 40 ℃,2 kinds of 2-layer (a layer/B layer 5: 45 in terms of discharge amount) were coextruded, and cooled to solidify, to obtain an unstretched sheet, except that, a polyester film (sample) having a release layer having a thickness of 0.03 μm after drying on the a-layer side of a polyester film substrate having a thickness of 50 μm (5 μm/45 μm for a layer a/B) and an average surface roughness (Ra) of the release layer side surface of 0.5 μm was obtained in the same manner as in example 1.
The properties of the polyester film (sample) are shown in table 3 below, and the film had poor curling properties.
[ Table 1]
IA IB IC ID IIA IIB III
Coating liquid 1 5 0 0 0 30 0 65
Coating liquid 2 5 0 0 0 65 0 30
Coating liquid 3 15 0 0 0 30 0 55
Coating liquid 4 15 0 0 0 55 0 30
Coating liquid 5 35 0 0 0 30 0 35
Coating liquid 6 35 0 0 0 0 30 35
Coating liquid 7 0 35 0 0 30 0 35
Coating liquid 8 50 0 0 0 20 0 30
Coating liquid 9 0 0 5 0 50 0 45
Coating liquid 1O 0 0 15 0 50 0 35
Coating liquid 11 0 0 0 35 30 0 35
[ Table 2]
Figure BDA0002623023970000311
[ Table 3]
Figure BDA0002623023970000321
The above Table 2 confirms the 1 st and 2 nd polyester films of the present invention, and the above Table 3 confirms the 3 rd polyester film of the present invention.
From the results of the above examples and the results of the tests carried out by the present inventors so far, it is known that: when the transmission density OD value of the polyester film is 0.10 or more, the visibility of the polyester film at the time of transfer can be made excellent.
In addition, it is known that: when a particle-containing layer containing particles having an average particle diameter of 2.0 μm or more is formed on one side or both sides of a base material layer and a release layer is further formed on the surface of the particle-containing layer, the surface of a polyester film can be appropriately roughened and a desired matte feeling can be transferred to an object.
In industryIs available to
The polyester film 10 is excellent in visibility at the time of transfer, i.e., visibility, and has a roughened film surface, and therefore, even if a release layer is formed, the roughened state is not smoothed, and a desired matte feeling can be imparted to an object, and therefore, the polyester film can be suitably used for applications of transferring a matte surface to an object, particularly, a surface-forming polyester film for an electromagnetic wave shielding member.
Description of the reference numerals
1: polyester film
11: polyester film substrate
111: substrate layer
112: particle-containing layer A
113: release layer

Claims (15)

1. A polyester film characterized by comprising a polyester film base material having a particle-containing layer containing particles having an average particle diameter of 2.0 [ mu ] m or more, wherein the polyester film has a transmission concentration OD value of 0.25 or more.
2. A polyester film characterized by comprising a polyester film base material, wherein the polyester film base material comprises a particle-containing layer (A) containing particles having an average particle diameter of 2.0 [ mu ] m or more on one side of a base material layer, and a particle-containing layer (B) containing particles having an average particle diameter of 2.0 [ mu ] m or more on the other side of the base material layer, and the content of the particles having an average particle diameter of 2.0 [ mu ] m or more in the particle-containing layer (B) is smaller than that in the particle-containing layer (A).
3. The polyester film according to claim 2, wherein the polyester film has a transmission concentration OD value of 0.10 or more.
4. The polyester film according to claim 1, wherein the polyester film base material is composed only of a particle-containing layer containing particles having an average particle diameter of 2.0 μm or more.
5. The polyester film according to claim 1 or 4, wherein a release layer is provided on at least 1 surface of the particle-containing layer.
6. The polyester film according to claim 2 or 3, wherein a release layer is provided on the surface of the particle-containing layer A.
7. The polyester film according to claim 5 or 6, wherein a surface of the release layer side has a glossiness of 30% or less.
8. The polyester film according to any one of claims 5 to 7, wherein the release layer side surface has an average surface roughness (Ra) of 0.1 to 2.0 μm.
9. The polyester film according to any one of claims 1 to 8, wherein the particles having an average particle diameter of 2.0 μm or more are organic particles.
10. The polyester film according to any one of claims 1 to 8, wherein the particles having an average particle diameter of 2.0 μm or more are silica particles.
11. The polyester film according to any one of claims 1,4 and 5, wherein the particle-containing layer contains metal compound particles.
12. The polyester film according to any one of claims 2,3 and 6, wherein any one of the substrate layer, the particle-containing layer A and the particle-containing layer B or 2 or more layers thereof contains metal compound particles.
13. A polyester film according to any one of claims 5 to 8, wherein the release layer contains a release agent.
14. The polyester film according to any one of claims 5 to 8 and 13, wherein the release layer has a crosslinked structure derived from a crosslinking agent.
15. A polyester film for surface shaping of an electromagnetic wave shielding member, which comprises a particle-containing layer containing particles having an average particle diameter of 2.0 [ mu ] m or more, and which has a transmission concentration OD value of 0.10 or more.
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